Extensive anatomical pilot studies in 75 mice suggest a new concept of organizing sensory-limbic interrelations in the forebrain. Small HRP injections along the insulotemporal cortex (ITC) revealed four "modules": Each module receives direct, modality specific sensory inputs from thalamus and cortex and projects heavily to discrete parts of the amygdala and hippocampal region. Each module's sensory affiliation is with either the taste/visceral, somesthetic, auditory or visual system. Each module also gets inputs back from the amygdala and hippocampal region and sends outputs back to its thalamic and cortical affiliates. Thus there are substantial, organized and remarkably direct circuits over which sensory and limbic systems may functionally interact. But important questions about ITC modules' topographical and functional organization cannot be resolved in the small mouse brain. Hence, we will investigate these modules with pathway tracing methods and single unit recording in the alert, restrained rabbit--a preparation that eliminates anesthetic effects on neural activity. Anatomy: HRP and isotope injections will be used to delineate the afferent and efferent connections of all four modules. The larger rabbit brain will obviate the label spread-problem that hinders the analysis of some short ITC connections and let us search for topography and laminar organization in each module's sensory-limbic circuits. Physiology: 1. The functional organization of each ITC module will be studied by characterizing and mapping the distribution of single unit's responses to specific, natural stimuli. At the end of each recording experiment the physiologically characterized module's connections will be determined with anatomical methods. 2. Activity of units in the amygdala to stimuli found appropriate for a module will be studied before and after ITC lesions to evaluate ITC-mediation of sensory control over the amygdala. Our experiments should provide a cellular neurobiological basis for understanding how forebrain sensory and limbic systems functionally interact and cooperate to modulate hypothalamic function.